It took me some research to get this proved instructions to work for any kind of USB Stick and any Linux/ubuntu distro to boot from.
Any usb-creator GUI did not work (for me) and also caused some bugs…
[Current issue at the releases 15.04 and 15.10] There are problems with the Startup Disk Creator alias usb-creator, if you try to create a 15.04 boot drive from the versions 12.04 LTS and 14.04 LTS of Ubuntu. See this link to the release notes https://wiki.ubuntu.com/UtopicUnicorn/ReleaseNotes#Boot.2C_installation_and_post-install. Unetbootin works from Ubuntu 12.04.5 and 14.04.2 (can make a working USB boot drive for Ubuntu 15.04), but the bug is still there in Startup Disk Creator (tested April 29 2015 (and October 22 for 15.10))
Continue reading Creating a bootbale USB Stick from Xubuntu ISO file on command line (Update)